Chronic and episodic acidification of Adirondack streams from acid rain in 2003-2005.
Limited information is available on streams in the Adirondack region of New York, although streams are more prone to acidification than the more studied Adirondack lakes. A stream assessment was therefore undertaken in the Oswegatchie and Black River drainages; an area of 4585 km(2) in the western part of the Adirondack region. Acidification was evaluated with the newly developed base-cation surplus (BCS) and the conventional acid-neutralizing capacity by Gran titration (ANC(G)). During the survey when stream water was most acidic (March 2004), 105 of 188 streams (56%) were acidified based on the criterion of BCS < 0 microeq L(-1), whereas 29% were acidified based on an ANC(G) value < 0 microeq L(-1). During the survey when stream water was least acidic (August 2003), 15 of 129 streams (12%) were acidified based on the criterion of BCS < 0 microeq L(-1), whereas 5% were acidified based on ANC(G) value < 0 microeq L(-1). The contribution of acidic deposition to stream acidification was greater than that of strongly acidic organic acids in each of the surveys by factors ranging from approximately 2 to 5, but was greatest during spring snowmelt and least during elevated base flow in August. During snowmelt, the percentage attributable to acidic deposition was 81%, whereas during the October 2003 survey, when dissolved organic carbon (DOC) concentrations were highest, this percentage was 66%. The total length of stream reaches estimated to be prone to acidification was 718 km out of a total of 1237 km of stream reaches that were assessed.
Lawrence
Gregory B
GB
U.S. Geological Survey, 425 Jordan Road, Troy, NY 12180, USA. glawrenc@usgs.gov
Roy
Karen M
KM
Baldigo
Barry P
BP
Simonin
Howard A
HA
Capone
Susan B
SB
Sutherland
James W
JW
Nierzwicki-Bauer
Sandra A
SA
Boylen
Charles W
CW
D015258:Acid Rain / Q000032:analysis*; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D009518:New York; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D013997:Time Factors; D014872:Water Movements
D015258:Acid Rain